Differentiated cognition of the effects of human activities on typical persistent organic pollutants and bacterioplankton community in drinking water source

Accelerated urbanization in developing countries led to a typical gradient of human activities (low, moderate and high human activities), which affected the pollution characteristics and ecological functions of water to varying degrees. However, the characteristics of the occurrence of typical persistent organic pollutants, including organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs), and bacterioplankton associated with the gradient of human activities in drinking water sources have been lacking. Our study focused on a representative case – the upper reaches of the Dongjiang River (Pearl River Basin, China), a drinking water source characterized by a gradient of human activities. A comprehensive analysis of PAHs, OCPs and bacterioplankton was performed using gas chromatography-mass spectrometry (GC-MS) and the Illumina platform. Moderate human activity could increase pollution from OCPs and PAHs due to local agricultural activities. The gradient of human activities obviously influenced the bacterioplankton community composition and interaction dynamics. Low human activity resulted in low bacterioplankton diversity. Co-occurrence network analysis indicated thunder moderate human activity could promote a more modular organization of the bacterioplankton community. The structural equation model showed that nutrients can exert a negative influence on the composition of bacterioplankton, and this phenomenon did not change with the gradient of human activities. OCPs played a negative role in shaping bacterioplankton composition at low and high human activities, but had a positive effect under moderate human activity. In contrast, PAHs showed a strong positive effect on bacterioplankton composition under low and high human activities and a weak negative effect under moderate human activity. Overall, these results shed light on the characteristics of the occurrence of OCPs and PAHs and their ecological effects on bacterioplankton in drinking water sources along the gradient of human activities.